1. Field
Example embodiments relate to an image forming apparatus, for example, an electrophotographic copier or inkjet copier, reduces the number of signal lines.
2. Description of the Background Art
Image forming apparatuses, such as digital photo copiers, facsimile machines, laser printers and the like, may be equipped with numerous detachable units, and these units may be provided with sensors as detectors for detecting their respective operating statuses. The detection signals from these sensors may be supplied to a controller (CPUs and so forth) of an image forming apparatus, and the signal lines provided for this purpose may be numerous.
With image-forming apparatuses being equipped with color capabilities, higher performance and/or greater functionality, the number of sensor signal lines has shown a tendency to grow. Further, in addition to detection result signals (data signals), power supplies are also needed to make use of these detectors. Inputting the respective detection signals from a larger number of detectors into a CPU or other such image forming controllers may require a larger number of signal lines and power lines, and image forming controllers may increase in size. Further, because image forming controllers may be provided in locations that are apart from these detectors and respective types of detectors, the larger number of signal lines, as well as the fact that these signal lines may wrap all around inside an apparatus have become bigger obstacles to making such apparatuses simpler, smaller and/or less costly.
Accordingly, a number of proposals have been put forward in the past for solving these problems. One such proposal includes an image forming apparatus, which provides a detachable unit with an I/O expander connected by a serial bus, and which has a controller for identifying the type of a detachable unit by the status of the input port of this I/O expander. In this image forming apparatus, the number of signal lines connecting a unit with the apparatus main body is reduced by identifying the type of unit in accordance with the status of the input port of the I/O expander.
Another proposal includes an image forming apparatus, a forwarding clock is set, when it is L level. The forwarding clock is image serial data, when the forwarding data taken at the time of forwarding data standing up. The forwarding data which stands up is control signal, when it is “H” level. The image serial signal and the control signal are transferred in a common signal line in the image forming apparatus.
However, according to this past proposal for an image forming apparatus, the signal lines for each detachable unit comprise a power line, data line, clock line, and ground line, and when viewed in terms of the apparatus as a whole, signal line reduction is still insufficient.
If the image serial signal and the control signal are transferred in a common signal line in the image forming apparatus, the signal line which is input and output to the image forming controller becomes larger.
Another problem is that when the system configuration (number of input/output devices) changes, suitable control must be provided, leading to higher costs.
FIG. 11 shows an example of a system configuration for a basic engine of an image forming apparatus.
Within the main body of the apparatus of the image forming apparatus shown in FIG. 11, a developer unit 41, photosensitive body unit 42, intermediate transfer unit 43, paper feeding unit 44 and/or fixing unit 45 may be connected as a plurality of detachable units to image forming controllers 40, which may have a CPU (Central Processing Unit). Signals showing the detachable status of these detachable units relative to the apparatus main body may each be input individually as input signals from detectors provided for the respective units. Other input signals include detection signals from detectors such as a temperature/humidity sensor 51 for detecting the temperature and humidity inside and outside the apparatus, a contact separation sensor 52 for detecting location/status information for a contact separation mechanism driven at image formation time, as well as a recording medium and the like, and/or a toner concentration detection sensor 54. Signal lines for a paper size detection sensor 53, which detects the size of a piece of paper, a paper supply cassette sensor and so forth also account for a plurality of bits, and may increase the number of signal lines. Although not shown in FIG. 11, there also may be a high voltage source feedback signal. Furthermore, although not shown in FIG. 11, a motor, clutch/solenoid for driving the mechanical systems may be connected to the image forming controller output devices.
Further, using these detectors may require power supplied in addition to detection result signals (data signals). Inputting the respective detection signals from the plurality of detectors into the image forming controller 40 may require numerous signal lines and power lines, causing image forming controller 40 to increase in size. Further, because image forming controller 40 may be located apart from these detachable units and respective types of detectors, the large number of signal lines, as well as the fact that these signal lines wrap all around inside the apparatus may be obstacles to making the apparatus simpler, smaller and/or less costly.